Mitosis
by Sidney Sussex
Summary: A cycle of progression for DI Lestrade and Sherlock Holmes.  Rated for themes and language.


_I neither own nor profit from any of these characters; they are the property of Sir Arthur Conan Doyle, Steven Moffat, Mark Gatiss and the BBC._

_If you see something that you think ought to be changed or improved, please feel free to let me know, if you'd like. Constructive criticism is always welcome._

_Special thanks to ImpishTubist for having read this over for me._

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><p><em>Mitosis: the process by which one alone becomes two together.<em>

Prophase

Everyone thinks Lestrade and Sherlock met over a body. They didn't. In fact, crime scenes didn't even enter into it for days.

In actuality, Sherlock had managed to release something so noxious into his laboratory at Barts that the entire wing of the building had had to be closed off for a week. Lestrade had been called down to the Forensic Services department the next day to deal with an "unauthorized visitor" who had taken over Anderson's space and equipment and was generally being a nuisance.

After having gotten over his incredulity at the idea that an "unauthorized visitor" could just walk into a laboratory full of sensitive evidence in the headquarters of the largest police force in England, he had gone to address the issue. His arrival had been greeted with an exasperated sigh and a request. "Pass me my phone, will you?"

Somehow, Lestrade had found himself passing the tall, darkly good-looking intruder his mobile phone. And hesitating a fraction of a second too long with it, so that the other man's fingers brushed against his own as he took it. And parlaying that split second, that burning hint of skin on skin, into a low and smouldering eye contact, gazes locked –

– until Anderson loudly demanded the return of his laboratory bench.

Lestrade _should_ have arrested Sherlock, or, at the very least, sent him packing.

What he _did_ was find an empty space in a chem/tox laboratory near the morgue, which he let Sherlock use at night until his wing at Barts re-opened.

Had he known it was the first step into a lifetime of being complicit in Sherlock's crimes, he still wouldn't have been able to help himself.

Metaphase

Sherlock shows up at any crime scene he's called to (and a fair few he isn't), as long as he deems them interesting enough. He tackles them all with the same ill-disguised enthusiasm and total disregard for social norms and rules. But Lestrade knows that Sherlock's favourite cases are the bloodless deaths – the ones where the killer is fastidious, takes his time, makes an effort to leave no evidence. It's not for the challenge, though that's what both of them will claim if either is ever asked. Sherlock just values care and precision. Even in a murderer.

Lestrade had called him out to the site of a murder with no visible signs of cause-of-death. Though the SOCO team had taken samples and would, in fact, have been able to discern the toxin eventually, it was an uncommon one and would have taken time. Sherlock, on the other hand, had provided the answer – batrachotoxin – after a cursory glance around the house and five minutes' typing on his mobile. He had, with many long-suffering looks, explained his reasoning to Lestrade, but the DI would be damned if he'd been able to follow along much past Sherlock's first sentence.

Still, they'd put a man in jail for it, and that satisfied Lestrade quite nicely.

Only afterward did he notice the heightened colour in Sherlock's cheeks, the way his eyes sparkled with pleasure. Sherlock looked giddy after ordinary cases; this time, he looked positively debauched. Lestrade, of course, had not been able to resist a press of fingers to Sherlock's side, a brief ghosting of breath over his shoulder, but the detective's reaction had utterly startled him.

In the end, he _had_ had some… moral objections. Or perhaps he was just uneasy about the prospect of getting caught. Either way, he'd tried to insist that Sherlock at least wait until they got back to his flat, but his resolve (or Sherlock's restraint, he wasn't sure which) had given out at some point during their quick stop off at New Scotland Yard to drop off his notebook, because he _definitely_ still remembers the rest of that evening, and he's pretty damn sure he doesn't recall any of its having taken place at his flat.

On the bright side, he hadn't been late to work the next morning.

Anaphase

At one point in his life, Lestrade was pretty good at meeting other men for quick, no-strings-attached liaisons. Or at least, he would have been, if he'd ever followed through with them. They were certainly _interested_.

But he'd never really been one to do that sort of thing. He'd had enough of that by the time he'd finished at uni (most of it admittedly vicarious), and anyway, he was far too busy at work. So, naïvely, he'd expected that Sherlock would be like those other men – interested, but only insofar as Lestrade was a quick shag after a night's drinking (or, in Sherlock's case, a night's deducing).

This made it terrifying to find that, for weeks after that first time, he _still wanted_ to grab Sherlock at crime scenes, pull him aside, and kiss him breathless. He _still wanted_ to do terrible things to those tight shirts for no reason other than the sin of covering Sherlock's body. He _still wanted_ – God help him, he still wanted _that night_, and he couldn't stop thinking about it.

And yet, at the very next opportunity (ye gods, no one had warned him there would be a _next opportunity_), he turned Sherlock down cold.

_Fuck_, said his brain, with a panicked glance around to make sure no one else had heard Sherlock's _very_ not-safe-for-work suggestion.

"No," he said aloud, and Sherlock's startled glance jolted something in him.

_Fuck_, said his brain again that night, shower turned up far too hot, one hand braced against the wall and fully aware that this could have been a team effort instead of a solo flight.

"_Yes_," he gasped aloud, and fucking hell, he was _still_ thinking about Sherlock.

It was an extremely long time before any other thoughts entered his head, and when they did, the one that resounded was, Why? Sherlock had offered – Sherlock had _asked_ – and he had flat-out refused.

_Why?_

It took three more increasingly-inappropriate propositions and three more abject refusals, before he finally figured it out.

This wasn't about one night. He'd had that. And it had been good – damned good – fucking _amazing_, all right? The memory of it _still_ woke him up at night. But that wasn't what he wanted. Not at _all_.

Once, it might just have been about that – those careful, precise fingers at crime scenes; those mesmerizing eyes piecing together evidence; that darkly thrilling attraction that bubbled up when their eyes met. Now, though, now he _knew_ Sherlock. And knowing him made all the difference.

He wasn't going to settle for a night, or even for many nights. Nights were meaningless. He didn't want meaningless, and he wasn't going to get anything else, so he would have nothing.

Sherlock asked again. He swallowed hard, said no.

He still remembers all those refusals, all that time spent fending off Sherlock to save himself. He still wonders why the _hell_ he never thought to question why Sherlock didn't _stop_ asking.

Telophase

It had become something of a routine. Sherlock would show up, solve the case (or not; sometimes it wasn't that easy and he had to come back to the Yard, and Lestrade thanked any deities that might exist for Sherlock's distaste for panda cars) and conclude by whispering in Lestrade's ear. Lestrade, in his turn, would flush hot and turn away, thinking furiously of football and England and the piles of paperwork awaiting him, hoping against hope that none of his team had heard.

Still, he went on saying no, losing sleep, and wondering when Sherlock would give it up as a bad job and just bloody leave him alone already.

He'd forgotten about the lock-picking.

For once, he'd gotten off work not _too_ long after midnight, and he'd gone straight home. He'd been promising himself a good night's sleep, congratulating himself on having dodged whatever new torture Sherlock had devised for him, reassuring himself that he _wanted_ to dodge it. He'd actually already been in bed. Not asleep – and not doing _that_, thank God – but just about ready to drift off, so he'd somehow missed the sound of his front door opening, the footsteps on the stairs.

He _didn't_ miss the shaking of the mattress, the warm weight sliding in on his left, and he jerked away so forcefully he nearly fell off the other side of the bed. A moment later he was standing, one hand holding the sheet up over his body, the other on the bedside light switch.

"Sherlock, _what the hell_ – "

And then he realized what the detective was (or rather _wasn't_) wearing, and completely lost the ability to speak.

"You were proving singularly unresponsive to my encouragement," said Sherlock, his voice as calm and even as if he were sitting in Lestrade's office, giving a statement. "I decided other means were necessary."

"Sherlock, no means no! Whether I say it to you fully dressed at a crime scene or – or – "

"Naked in your bed with – " and he let his gaze travel meaningfully up and down Lestrade, sheet notwithstanding.

"Sherlock, get out of here before I – just… get… _out_. And put some bloody clothes on."

With those last few words, Lestrade's surge of energy was spent and he sank down onto the edge of the bed, still clutching the sheet. "Let me sleep, Sherlock. I'm tired. You're not helping."

"Why do you keep refusing?"

"What?" he sighed.

"Why do you keep saying no to me? You don't _want_ to."

"You have no idea what I…" but of course he did. This was Sherlock Holmes, after all. "Yes, well, cooler heads prevail, don't they? Now do you _mind_?"

"Yes. Very much. I want to understand."

"Well, this is one mystery you're going to have to live without solving."

Sherlock opened his mouth to answer, then stopped, a frown gathering. "You think this is a… case?"

"Case, boredom prevention, mildly intriguing question, I don't know, do I? I probably don't even _want_ to know. Just stop using _me_ for it, all right? Look at you, it's not like you'll have any trouble finding some other poor bastard to experiment on instead."

Sherlock did look at himself, but apparently found no enlightenment there, so he looked back up at Lestrade instead. "_Experiment_ on?"

"Whatever you want to call it. It's half one, Sherlock, don't play semantics with me."

"I… Whatever you may think, Lestrade, this is not a… game. Nor is it an experiment."

His retort all queued up and ready to go, Lestrade suddenly found that it no longer matched the conversation.

"Sorry?"

"What gave you that impression?"

"I… _you_. _You_, with your – I mean – what _is_ it, then?"

Sherlock's face was solemn. "I'm not sure."

"Not sure?"

"If this were an intellectual problem, I could satisfy it with any test subject I chose. Yet if it were a physical issue, I could remedy it… single-handedly." Lestrade snorted, but despite the fact that his wording had been deliberately chosen, Sherlock's expression didn't change. "None of this explains the fact that I feel the need to ask _you_."

Lestrade blinked.

"Have you, ah, _tried_ asking anyone else?"

"I have explored all possible controls."

"… And?"

"No. Somehow the fact that it's _you_ is significant."

Lestrade blinked again, but slid farther onto the bed and tucked his feet back under the covers. No sense in carrying on an actual conversation while standing awkwardly in his own bedroom holding up a sheet.

For some reason, this confession of Sherlock's was somehow _more_ unexpected than his abrupt arrival naked in Lestrade's bedroom. And what _that_ said about the two of them, Lestrade definitely did not want to know.

"So you've ruled out intellectual and physical needs."

"I wouldn't have come here for either."

Ignoring the slight, Lestrade leant back against the headboard, legs stretched out in front of him. This – despite the faint voice at the back of his head that said this might be a good thing, a _very good thing_ – was a bit much for him to process, and he suspected it would be even more overwhelming for Sherlock.

"What does that leave, then?"

"I don't know."

Lestrade looked wonderingly at him. "You honestly haven't even _considered_ the possibility of an emotional attachment, have you?"

"High-functioning sociopath, Lestrade. Do your research."

"I don't believe a word of it."

"Sociopaths not big on emotion."

"Shut up or I'll prove it to you."

_That_ got Sherlock's attention fast. "How?"

"_Experimentally._"

Sherlock stared at him, eyes widening slightly in anticipation of an experiment – but it wasn't enough.

"You really don't think there could be any sort of a connection here?" And he'd never felt so stupid, saying this to a man who was _naked in his bed_.

Sherlock glanced away uncertainly. He _really_ didn't know.

"Right," said Lestrade, shifting even further into the middle of the bed, and he reached out and pulled Sherlock in close. The younger man's muscles tensed, but he'd been expecting that, and gave Sherlock a moment to acclimatize to the weight of Lestrade's arm around his shoulders, the closeness of their new position.

True, they'd been a lot closer than this, but…

"Not quite so easy when you can't just say 'no strings attached,' is it?"

He was expecting the glare he received, and instead of being bothered by it, just laughed, drew Sherlock even closer, and pressed his lips to the furrowed brow.

"Think about it," he murmured. "It's not entirely a bad thing."

Then he released Sherlock, slipped down further under the covers, and lay back.

"What are you doing?"

"Going to sleep, Sherlock. It's after two o'clock in the morning. You ought to be doing the same." He reached one hand out and snapped off the bedside lamp.

Sherlock's gaze glittered in the dark for a moment, reflecting the distant London lights just barely visible through Lestrade's bedroom window. He sat motionless for a moment, then sighed and pushed back the covers to get up.

A hand snaked around his wrist. "What are you doing?"

He gestured at the shadowy doorway. "You did say to leave…"

"Don't be stupid." And Lestrade pulled him back down to lie next to him, strong arms wrapped around Sherlock's thin frame, face buried in dark, curled hair.

He's never forgotten that night. He likes to think of it, privately, as Sherlock's rebirth – the day he became something he didn't know he could be.

Interphase

Everyone thinks Lestrade and Sherlock met over a body, because it's the only time when Sherlock really looks _alive_, eyes sparkling and cheeks flushed in excitement, grand gestures and sweeping swirls of coat as he barks out the things he thinks should have been obvious to everyone. They can't imagine Sherlock's being tolerable in any other situation, not that they find his company particularly enjoyable at crime scenes, either.

But they haven't seen what he's like when an experiment goes right and he comes running – _running_, full-tilt – up the stairs to exclaim at the top of his lungs about the structure of a protein in the blood, or the age of an ancient pottery fragment, or the reactivity of a rare insect venom.

They haven't seen what he's like when he breezes in from a day spent exploring London, visiting each tiny nook and cranny and side street to see how all of it has changed since the last time he followed the same trails. They haven't seen dishevelled hair and closed eyes and the quiet joy that closeness to his city brings to Sherlock. They wouldn't understand it if they did.

They haven't seen what he looks like in bed, in the half-light of the streetlamp through the open curtains, warm to the touch and trembling and completely overwhelmed, because this isn't – and will never be – something Sherlock is used to. He'll never take any of this for granted, because until now, he'd never even guessed at it. That maybe this isn't just another way to use people; that maybe this is more than just hormones and neurotransmitters and physiology.

They haven't seen the way Sherlock comes alive when Lestrade whispers softly, "I love you," and they never will, because that, _that_, is just for the two of them and no one else.

It doesn't matter what everyone thinks.

The truth is so much better than they could ever guess.


End file.
